Modulator diaphragm and method of assembly

ABSTRACT

A vacuum modulator is disclosed having a peripherally tabbed diaphragm leading through and externally of folded clamping flanges to provide a visible cue of the registry of the diaphragm relative to the clamping flanges.

United States Patent 1 1 3,585,905

721 Inventors StuartAJHason 2,335,276 11/1943 Heintz 92/99 nria e mcom;2,738,808 3/1956 HartzelletaL. 92/99x Ben L. Ehlin, Brooklyn, N.Y.2,840,339 6/1958 Price 92/103 X [21] App]. No. 833,567 2,985,196 5/1961Brunner 92/99 X [22] Filed June 16, 1969 3,081,793 3/1963 Flatt etal.... 92/100 X [45] Patented June 22,1971 3,151,568 10/1964 Hood etal.. 92/100 X [73] Assignee Casco Products Corporation 3,208,721 9/1965Mcl-lugh 92/103 X Bridgeport, Conn. 3,283,670 1 111966 Taplin 92/99Primary Examiner-Edgar W. Geoghegan s41 MODULATOR DIAPHRAGM AND METHODor Emmi'wrilrwm Cohen ASSEMBLY Anarneys-E. Mannlng Giles, J. PatrickCagney, Peter S. 3 Claims, 5 Drawing Lucyshyn and Richard G. Kinney [52111.8. c1. 92/100 511 1111.01 F16] 3/00 501 FieldoiSeai-ch 92/100,103,103 5, 103 M, 98, 99,101, 93, 89, 47, 48; 73/410 ABSTRACT: A vacuummodulator is disclosed having a [56] new? Cited peripherally tabbeddiaphragm leading through and externally UNITED STATES PATENTS of foldedclamping flanges to provide a visible cue of the regis- 2,306,76812/1942 Wile 92/100 X try of the diaphragm relative to the clampingflanges.

MODULATOR DIAPHRAGM AND METHOD OF ASSEMBLY This invention relates topressure responsive diaphragmtype linear actuators and more particularlyis concerned with an improved diaphragm construction for a transmissionmodulator or similar device.

In a typical vacuum modulator such as is utilized in an automatictransmission system of an automobile, a differential pressure capsule iscomprised of a pair of mating rigid casing shells spanned by a flexiblydistortable internal diaphragm to define separate pressure chamberstherein, each exposed to different pressure conditions. One chamber issubjected to engine manifold vacuum. A center plate structure isassociated with the diaphragm and is arranged to engage an external pushrod leading through the other chamber to control a throttle valve inaccordance with changes in manifold pressure. It is required that thediaphragm provide a permanent fluidtight seal between the chambers andit has been the practice to provide one of the casings with acircumambient seal rim portion in the form of an outwardly directedannular flange and to provide the other casing with a mechanicallyflared end for defining a confronting annular flange and a marginal lipwhich may be crimped about the first flange in a reverse bendconfiguration. A generally U-shaped groove is defined between the firstflange and the crimped flange, with the periphery of the diaphragm beingdisposed in the U-groove.

In the prior art practice, the diaphragm is completely masked by theclamping flanges so that there is uncertainty as to whether thediaphragm has been accurately registered and secured along its entireperiphery. It has not been practical to utilize oversize diaphragms asthe large diameter marginal portions, when folded over to occupy aregion of smaller diameter, tend to bunch and thereby interfere with theuniformity of the clamping and sealing relationships that are desired.

Where a bunching condition develops, there is the further problem thatcuttingor tearing of the diaphragm may occur leading to actual diaphragmpullout.

In accordance with the present invention, a diaphragm construction isprovided which solves these difficulties and, in ad dition, provides areliable visible cue in the final assembly which pennits the assembler,tester and user to see that the diaphragm is in properly registeredrelationship to the clamping rims. If the diaphragm is offcenter,improper diaphragm assembly is indicated.

Thus, in accordance with this invention, there is provided adifferential pressure capsule having a flexibly distortable internaldiaphragm spanning an intermediate region thereof to define separatepressure chambers therein, the capsule being comprised of mating rigidcasing shells having confronting circumambient clamping rim portionscooperable to define a circumambient groove for receiving and gripping acircumambient portion of the diaphragm in edge-sealed relation, thediaphragm having integral edge tabs spaced along the periphery of thediaphragm and projecting externally of the groove to provide visibleindication of the registry of the diaphragm relative to the clamping rimportions.

The embodiment of the invention illustrated herein is a vacuum modulatorhaving a diaphragm of laminar construction comprised of a fabric layercovered with an elastomer coating, the diaphragm having a configurationto accommodate the required travel and the casing shells havingconfronting clamping flanges, one flange having a marginal lip to bereverse bent about the other by a mechanical crimping operation todefine a U groove.

The edge of the diaphragm has a reverse bend configuration like that ofthe U-groove resulting in the larger diameter portion of the diaphragmextending inwardly through a smaller diameter region of the groove. Thespaced tab portions on the edge of the diaphragm project externally ofthe U-shaped groove without objectionable bunching.

Other features and advantages of the invention will be apparent from thefollowing description and claims and are illustrated in the accompanyingdrawings which show structure embodying preferred features of thepresent invention and the principles thereof, and what is now consideredto be the best mode in which to apply these principles.

In the accompanying drawings forming a part of the specification and inwhich like numerals are employed to designate like parts throughout thesame:

FIG. I is a side elevational view of a vacuum modulator incorporating adiaphragm construction in accordance with this invention, the view beingshown partly in section to facilitate disclosure;

FIG. 2 is a fragmentary end view of the modulator of FIG. 1 withportions thereof broken away and sectioned;

FIG. 3 is a fragmentary plan view of the diaphragm prior to assembly;

FIG. 4 is an enlarged fragmentary sectional view through the clampingand seal regions of the device and is taken approximately as indicatedon the line 4-4 of FIG. 2; and

FIG. 5 is a diagrammatic view illustrating the method of assembly of themodulator.

Referring now to the drawings and particularly to FIG. 1, a fluidactuated control unit, designated generally at 10, is shown as a vacuummodulator for purposes of illustrative disclosure. The modulatorconsists of a differential capsule 11 having a flexibly distortableinternal diaphragm assembly 12 spanning an intennediate region of thecapsule to define separate pressure chambers 13 and 14 therein. Thecapsule is defined by a pair of mating rigid shells l5 and 16 which haveclamping n'm structures cooperable to grip a diaphragm in sealingrelationship therebetween.

The diaphragm assembly 12 is shown as including a flexible diaphragmelement 17 encircling a floating carrier 18 which is equipped withreinforcement plates 19, 20 for engagement with opposite faces of thediaphragm. The carrier 18 is shown equipped with fastener structure 18Fto secure the parts of the diaphragm assembly. The plate 20 serves as aspring seat for a load spring 21 located in the shell 15. The shell 15is provided with a connection fitting 15F to establish communicationbetween the chamber 13 and the engine manifold so that manifold vacuummay act to control the position of the diaphragm 17. The shell 16 isprovided with a threaded bushing 16T for connection to the transmissionsystem. An external push rod 22 leads through the threaded bushing MTand is acted upon by the fluid pressure in the transmission system toload the push rod against the carrier. Thus changes in manifold vacuumact on the modulator diaphragm to effect positioning of the push rod 22and thereby control the throttle valve.

In the illustrated embodiment, the flexibly distortable diaphragmelement 17 may be installed under maximum deflection or may have aslightly dished or corrugated shape in accordance with the requiredtravel stroke for the diaphragm. For this particular application, thediaphragm 17 preferably consists of a nylon fabric sheet covered with anelastomer coating. Typical elastomer materials suitable for this purposeinclude Buna N rubber or fluorosilicone rubber compounds.

In the illustrated embodiment, the casing shells are shown as metalstampings, the shell 15 having a clamping rim 23 in the form of anoutwardly directed annular flange and the shell 16, as initially formed,having a mechanically flared end providing a clamping rim 24 comprisedof a confronting flange 24 and a marginal lip 25 (see FIG. 5).

As finally assembled (see FIG. 4), the lip 25 has a reverse bendconfiguration and the diaphragm edge is gripped in a U configuration tooccupy the U-shaped groove that is defined between the clamping portions23, 24 and 25.

The diaphragm has integral edge tabs l7T spaced about its periphery, thetabs having a base region 178 normally located at the position indicatedin FIG. 4 to minimize bunching due to diameter differences associatedwith the folded configuration. The tabs l7T project externally of thegroove and along the sidewall of the shell 15 to present a visible cueof the registry of the diaphragm relative to the clamping portions. Itis apparent from'the drawings of the preferred embodiment that the edgetabs 117T constitute an annular array of uniformly spaced indicatorsspace along the entire periphery to indicate registry of the diaphragmalong its entire periphery. As is apparent in FIGS. 1 and 2 the tabarray in the final assembly collectively and uniformly covers a majorperimetral portion of the visible surface of the shell 15 at the regionof such surface which is adjacent the U-shaped groove. Accurate registryis important for assuring adequate sealing and for avoiding bunching.

The assembly of the modulator is best explained in relation to FIG. 5wherein the casing shell 16 is shown with its flared end facing up andwith an external assembly pin 26 projecting through the threaded bushing16'! and engaging the carrier 18 to support the diaphragm assembly 12 sothat the diaphragm 17 is lightly above the marginal lip 25 and has itsedge projecting outwardly of the lip. This diaphragm positioncorresponds to the maximum deflection condition encountered duringoperation of the modulator. The casing shell 15 and coil spring 21 arelowered onto the shell 16 and spring seat 20, respectively, while thediaphragm position is maintained. The lip 25 then is crimped intoreverse bend configuration about the flange 23 to complete the assembly.The diaphragm 17 will then assume the relaxed configuration in which itis shown in FIG. 1 and can accommodate a predetermined travel strokewithout stretching.

Thus, while preferred constructional features of the invention areembodied in the structure illustrated herein, it is to be understoodthat changes and variations may be made by those skilled in the artwithout departing from the spirit and scope of the appended claims.

The embodiments of the invention in which an exclusive property ofprivilege we claim are as follows:

l. in a differential pressure capsule having a flexibly distortableinternal diaphragm spanning an intermediate region thereof to defineseparate pressure chambers therein, the capsule being comprised of firstand second mating rigid casing shells having confronting circumambientclamping rim portions cooperable to define a circumambient groove forreceiving and gripping a circumambient portion of the diaphragm inedge-sealed relation, the first shell rim portions having an annularoutwardly directed flange and the second having an annular flangepresenting an opposed flange portion and a reverse bend lip portiondefining a circumambient U- shaped groove for the edge of the diaphragm,the improvement comprising an annular array of uniformly spaced integraldiaphragm edge tabs spaced along the entire periphery of the diaphragm,said tabs projecting externally of the groove to collectively anduniformly cover major perimetral portion of the surface on said firstshell rim portion immediately above said groove to provide visibleindication of the registry of the diaphragm relative to the clamping rimportions.

2. In a method of assembling a differential pressure capsule thatincludes a flexibly distortable diaphragm and a pair of rigid casingshells having confronting circumambient rim portions for gripping thediaphragm in sealing relation about its periphery, the steps for formingone of the shells with an annular peripheral flange of predetermineddiameter forming the other shell with a confronting flange for the firstflange and with a marginal lip, locating a diaphragm that has an annulararray of uniformly spaced peripheral tab portions in position to spanthe confronting flange with the tab portions of the diaphragm projectingoutwardly of the lip, seating the flange of the first-named shellagainst the diaphragm portion that spans the confronting flange, andbending the lip into reverse bend configuration about the first-namedflange for folding and sealing the edge of the diaphragm into aU-configuration wherein the tab portions project along an externallyvisible region of the first-named shell and uniformly cover asubstantial portion of said externally visible region.

3. A method in accordance with claim 2 and including locating andholding the diaphragm in a maximum travel configuration during seatingof the flange of the first-named shell and during bending of said lip.

1. In a differential pressure capsule having a flexibly distortableinternal diaphragm spanning an intermediate region thereof to defineseparate pressure chambers therein, the capsule being comprised of firstand second mating rigid casing shells having confronting circumambientclamping rim portions cooperable to define a circumambient groove forreceiving and gripping a circumambient portion of the diaphragm inedge-sealed relation, the first shell rim portions having an annularoutwardly directed flange and the second having an annular flangepresenting an opposed flange portion and a reverse bend lip portiondefining a circumambient U-shaped groove for the edge of the diaphragm,the improvement comprising an annular array of uniformly spaced integraldiaphragm edge tabs spaced along the entire periphery of the diaphragm,saId tabs projecting externally of the groove to collectively anduniformly cover major perimetral portion of the surface on said firstshell rim portion immediately above said groove to provide visibleindication of the registry of the diaphragm relative to the clamping rimportions.
 2. In a method of assembling a differential pressure capsulethat includes a flexibly distortable diaphragm and a pair of rigidcasing shells having confronting circumambient rim portions for grippingthe diaphragm in sealing relation about its periphery, the steps forforming one of the shells with an annular peripheral flange ofpredetermined diameter forming the other shell with a confronting flangefor the first flange and with a marginal lip, locating a diaphragm thathas an annular array of uniformly spaced peripheral tab portions inposition to span the confronting flange with the tab portions of thediaphragm projecting outwardly of the lip, seating the flange of thefirst-named shell against the diaphragm portion that spans theconfronting flange, and bending the lip into reverse bend configurationabout the first-named flange for folding and sealing the edge of thediaphragm into a U-configuration wherein the tab portions project alongan externally visible region of the first-named shell and uniformlycover a substantial portion of said externally visible region.
 3. Amethod in accordance with claim 2 and including locating and holding thediaphragm in a maximum travel configuration during seating of the flangeof the first-named shell and during bending of said lip.